Question

Weak noncovalent attractions in the cell can be very strong in a nonaqueous environment. Some of these attractions are as strong as covalent interactions in a vacuum (their bond energy is approximately 340 kJ/mole), but become more than twenty-five times weaker (their bond energy becomes approximately 13 kJ/mole) in water. What type of attraction shows this phenomenon?

1) Electrostatic attractions
2) Hydrogen bonds
3) van der Waals attractions
4) Hydrophobic force
5) All of the above

Answer 1

Hydrogen bonds are significantly weakened in water compared to a nonaqueous environment due to the polar nature of water which competes for the bond, thus reducing its strength.

Step-by-step explanation:

The type of attraction that shows the phenomenon of being as strong as covalent interactions in a vacuum but becomes significantly weaker in water is the hydrogen bond. Hydrogen bonds are a strong type of dipole-dipole interaction that occurs when a hydrogen atom bonded to a highly electronegative atom, such as oxygen, exhibits a partial positive charge and is attracted to the negative part of a nearby molecule. In a nonaqueous environment, hydrogen bond energies can be quite high, but in water, where the polar molecules of water can interfere with and weaken these interactions, their bond energy reduces considerably. This weakening of hydrogen bonds in water is due to the high polarity of water molecules which compete for the hydrogen bonds with other entities, hence reducing their bond strengths.